evobackup-client now uses the default ed25519 key of the server

We used to prefer creating a specific one for backups, but everybody
kept thinking the wrong key was being used and "fixing" it. The
advantages of having a specific key for backups did not outweigh
the challenge of creating a culture change.

evobackup-client/defaults/main.yml

@@ -1,5 +1,6 @@
 ---
-evobackup_client__root_key_path: "/root/.ssh/evobackup_id"
+evobackup_client__root_key_path: "/root/.ssh/id_ed25519"
+evobackup_client__root_key_type: "ed25519"
 evobackup_client__cron_path: "/etc/cron.daily/zzz_evobackup"
 evobackup_client__cron_template_name: "zzz_evobackup"
 evobackup_client__mail: null

evobackup-client/tasks/ssh_key.yml

@@ -5,7 +5,7 @@
     name: root
     generate_ssh_key: true
     ssh_key_file: "{{ evobackup_client__root_key_path }}"
-    ssh_key_type: rsa
+    ssh_key_type: "{{ evobackup_client__root_key_type }}"
   register: evobackup_client__root_key
   tags:
     - evobackup_client